Wedge clutch with residual magnetism attenuation and pump with residual magnetism attenuation

ABSTRACT

A clutch, including: inner and outer races; a wedge plate; an electromagnetic actuator including a coil and an attenuating circuit. The coil is arranged to be energized by a power source to switch the wedge clutch between: a locked mode in which the inner and races are locked in a circumferential direction and a free-wheel mode in which the inner race is rotatable with respect to the outer race in the circumferential direction. The attenuating circuit includes a capacitor parallel with the coil and a switch wired to the capacitor. During the free-wheel mode: the switch is arranged to connect the capacitor to an electrical ground; and the electrical power source is arranged to energize the coil and charge the capacitor with a voltage. Following initiation of the locked mode: the switch isolates the capacitor from the electrical ground; and the capacitor discharges the voltage through the coil.

TECHNICAL FIELD

The present disclosure relates to a wedge clutch with an actuatorincluding an attenuating circuit for removing residual magnetism and apump including an attenuating circuit for removing residual magnetism

BACKGROUND

For known electromagnetic devices, windings in or around ferromagneticmaterial are energized to create magnet fields used to displacecomponents of the electromagnetic device. For example: a winding (coil)of a solenoid is energized to create a magnetic field displacing a pinsurrounded by the winding; and for a reluctance motor, circumferentiallydisposed windings of a stator are energized and de-energized in sequenceto create rotating magnetic fields that rotate a rotor for the pump.When windings are de-energized, residual magnetism remains in theferromagnetic material associated with the windings. The residualmagnetism resists displacement of the components to desired positions,for example, the pin for the solenoid returning to a pre-energizedposition, or continued rotation of the rotor for the pump.

SUMMARY

According to aspects illustrated herein, there is provided a wedgeclutch, including: an axis of rotation; an inner race; an outer racelocated radially outward of the inner race; a wedge plate radiallydisposed between the inner race and the outer race; an electromagneticactuator including a coil and an attenuating circuit. The coil isarranged to be energized by an electrical power source to displace thewedge plate, with respect to the inner race or the outer race, to switchthe wedge clutch between: a first locked mode of the wedge clutch, inwhich the inner race, the wedge plate, and the outer race arenon-rotatably connected for rotation of the inner race in a firstcircumferential direction; and a first free-wheel mode of the wedgeclutch, in which the inner race is rotatable, with respect to the outerrace, in the first circumferential direction. The attenuating circuitincludes: a capacitor wired in parallel with the coil; and a switchwired to the capacitor. During the first free-wheel mode: the firstswitch is arranged to connect the capacitor to an electrical ground; andthe electrical power source is arranged to energize the coil and chargethe capacitor with a voltage. Following an initiation of the firstlocked mode: the first switch is arranged to electrically isolate thecapacitor from the electrical ground; and the capacitor is arranged todischarge the voltage through the coil.

According to aspects illustrated herein, there is provided a wedgeclutch, including: an axis of rotation; an inner race; an outer racelocated radially outward of the inner race; a wedge plate radiallydisposed between the inner race and the outer race and including a firstcircumferential end and a second circumferential end; and anelectromagnetic actuator including a coil and an attenuating circuit.The coil: includes a first coil core piece fixedly connected to thefirst circumferential end and with an end enclosed by the coil; and isarranged to be energized by an electrical power source to draw the firstcoil core piece and the second circumferential toward each other toswitch the wedge clutch between a locked mode in which the inner race,the wedge plate, and the outer race are non-rotatably engaged forrotation of the inner race in a circumferential direction and afree-wheel mode in which the inner race is rotatable with respect to theouter race in the circumferential direction. The attenuating circuitincludes: a capacitor electrically wired in parallel with the coil; anda switch electrically connected to the capacitor. During the free-wheelmode: the first switch is arranged to connect the capacitor to anelectrical ground; and the electrical power source is arranged to chargethe capacitor with a voltage and energize the coil. Following aninitiation of the locked mode: the first switch is arranged toelectrically isolate the capacitor from the electrical ground; and thecapacitor is arranged to discharge the voltage through the coil.

According to aspects illustrated herein, there is provided a pump,including: a fluid inlet section; a fluid outlet section; a statoraxially between the fluid inlet section and the fluid outlet section; arotor axially between the fluid inlet section and the fluid outletsection, the rotor and the stator defining a fluid flow space radiallytherebetween; a movable inlet guide configured for guiding fluid flowfrom the fluid inlet section into the fluid flow space; a movable outletguide arranged to guide fluid flow from the fluid flow space into thefluid outlet section; and an attenuating circuit. The stator includes: aplurality of radially inwardly extending legs; and a plurality ofelectrical windings disposed about the plurality of radially inwardlyextending legs and arranged to be connected to an electrical powersource. The attenuating circuit includes: a capacitor electrically wiredin parallel with a first electrical winding of the plurality ofelectrical windings; and a switch electrically connected to thecapacitor. The rotor is arranged to be rotated inside of the stator byenergization of the plurality of electrical windings. During theenergization of the plurality of electrical windings: the switch isarranged to electrically connect the capacitor to an electrical ground;and the electrical power source is arranged to create a voltage in thecapacitor, following a de-energization of the plurality of electricalwindings: the switch is arranged to electrically isolate the capacitorfrom the electrical ground; and the capacitor is arranged to dischargethe voltage through the first electrical winding.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments are disclosed, by way of example only, withreference to the accompanying schematic drawings in which correspondingreference symbols indicate corresponding parts, in which:

FIG. 1 is a schematic block diagram of a wedge clutch with residualmagnetism attenuation;

FIG. 2 is a schematic wiring diagram of an attenuating circuit in FIG.1;

FIG. 3 is a graph of magnetic flux density and magnetic field strength;

FIG. 4 is a graph of electrical current through a coil and time, showingan oscillating waveform;

FIG. 5 is an exploded view of an example wedge clutch with residualmagnetism attenuation shown in FIG. 1;

FIG. 6 is a front view of the wedge clutch with residual magnetismattenuation shown in FIG. 5;

FIG. 7 is a cross-sectional view of an electromagnetic actuator of thewedge clutch with residual magnetism attenuation shown in FIG. 5;

FIG. 8 is a front view of a wedge plate of the wedge clutch withresidual magnetism attenuation shown in FIG. 5;

FIG. 9 is a front view of a wedge plate of the wedge clutch withresidual magnetism attenuation shown in FIG. 5;

FIG. 10 is a front view of inner races of the wedge clutch with residualmagnetism attenuation shown in FIG. 5;

FIG. 11 is a back view of a wedge plate of the wedge clutch withresidual magnetism attenuation shown in FIG. 5;

FIG. 12 is a back view of a wedge plate of the wedge clutch withresidual magnetism attenuation shown in FIG. 5;

FIG. 13 is a cross-sectional view generally along line 13-13 in FIG. 6;

FIG. 14 is an exploded view of an example wedge clutch with residualmagnetism attenuation;

FIG. 15 is a front view of the wedge clutch with residual magnetismattenuation shown in FIG. 14;

FIG. 16 is a front view of a wedge plate of the wedge clutch withresidual magnetism attenuation shown in FIG. 14;

FIG. 17 is a front view of a wedge plate of the wedge clutch withresidual magnetism attenuation shown in FIG. 1.4;

FIG. 18 is a front view of an inner race of the wedge clutch withresidual magnetism attenuation shown in FIG. 1.4;

FIG. 19 is a cross-sectional view generally along line 19-19 in FIG. 15;

FIG. 20 is front view of an example wedge clutch with residual magnetismattenuation;

FIG. 21 is an enlarged view of region 21 in FIG. 20;

FIG. 22 is a schematic cross-sectional view of a pump, with residualmagnetism attenuation;

FIG. 23 is an exploded view of the pump shown in FIG. 22; and

FIG. 24 is a front view of a stator, a rotor and a swash plate of thepump shown in FIG. 22.

DETAILED DESCRIPTION

At the outset, it should be appreciated that like drawing numbers ondifferent drawing views identify identical, or functionally similar,structural elements of the disclosure. It is to be understood that thedisclosure as claimed is not limited to the disclosed aspects.

Furthermore, it is understood that this disclosure is not limited to theparticular methodology, materials and modifications described and assuch may, of course, vary. It is also understood that the terminologyused herein is for the purpose of describing particular aspects only,and is not intended to limit the scope of the present disclosure.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood to one of ordinary skill inthe art to which this disclosure belongs. It should be understood thatany methods, devices or materials similar or equivalent to thosedescribed herein can be used in the practice or testing of thedisclosure.

FIG. 1 is a schematic block diagram of wedge clutch 100 with residualmagnetism attenuation.

FIG. 2 is a schematic wiring diagram of an attenuating circuit shown inFIG. 1. The following should be viewed in light of FIGS. 1 and 2. Wedgeclutch 100 includes: axis of rotation AR; outer race 102; inner race104; at least one wedge plate 106 radially disposed between inner race104 and outer race 102; and at least one electromagnetic actuator 107including attenuating circuit 108. Each electromagnetic actuator 107includes ferromagnetic material FM and coil 109 arranged to be energizedby source voltage Vs from electrical power source EPS to generatemagnetic field MF (only partially displayed in FIG. 2). In the exampleof FIGS. 1 and 2, each electromagnetic actuator 107 includes at leastone coil core piece 110 with: at least one end 105 fixedly connected toat least one wedge plate wedge plate 106; and at least one end 111enclosed by coil 109. The dashed lines in FIG. 2 enclose and designateelements that are connected to circuit 108, but not necessarily includedwith circuit 108. In an example embodiment (not shown), elementsenclosed and designated by the dashed lines in FIG. 2 are included incircuit 108. Note that coil 109 functions as an inductor.

Magnetic field MF displaces at least one wedge plate 106, with respectto outer race 102 or inner race 104, to switch wedge clutch 100 between:a first locked mode of wedge clutch 100; and a first free-wheel mode ofwedge clutch 100. In the first locked mode, inner race 104, wedge plate106, and outer race 102 are non-rotatably connected for rotation ofinner race 104 in one of circumferential direction CD1 or oppositecircumferential direction CD2. In the first free-wheel mode of wedgeclutch 100, inner race 104 is rotatable, with respect to outer race 102,in the one of circumferential direction CD1 or CD2.

Each attenuating circuit 108 includes: capacitor 112 wired in parallelwith coil 109 and switch 113 wired to capacitor 112. During the firstfree-wheel mode of wedge clutch 100: switch 113 is arranged to connectcapacitor 112 and coil 109 to electrical ground EG; and electrical powersource EPS is arranged to energize coil 109 and charge capacitor 112with capacitor voltage Vc. Following, or concurrent with, an initiationof the first locked mode: switch 113 is arranged to electrically isolatecapacitor 112 and coil 109 from electrical ground EG; and capacitor 112is arranged to discharge voltage Vc through coil 109.

Following the initiation of the first locked mode, voltage Vc incapacitor 112 and a voltage drop across coil 109 are arranged toalternately drive: electrical current EC1 through coil 109 in directionD1; and electrical current EC2 through coil 109 in direction D2,opposite direction D. Following the initiation of the first locked mode,current EC1 and current EC2: randomize residual magnetic fields inelectromagnetic actuator 107 or wedge plate 106; and attenuate residualmagnetic saturation in electromagnetic actuator 107 or wedge plate 106.As further described below, when coil 109 and charged capacitor 112(voltage Vc is present) are isolated from ground EG by switch 113,coil/inductor 109 and capacitor 112 operate as oscillating circuit OC,in which voltage Vc is discharged through currents EC1 and EC2.

In an example embodiment, attenuating circuit 108 includes switch 114.Switch 114: is electrically connected to capacitor 112 and coil 109; andarranged to electrically connect to electrical power source EPS.Following the initiation of the first locked mode, switch 114 isarranged to electrically isolate capacitor 112 and coil 109 fromelectrical power source EPS.

FIG. 3 is a graph of magnetic flux density B and magnetic field strengthH. The following should be viewed in light of FIGS. 1 through 3. Asenergy is applied to coil 109, magnetic flux is introduced into materialFM, causing magnetic field MF to form. When sufficient power issupplied, magnetic field MF reaches saturation point, B_sat shown inFIG. 3. When the power is removed from coil 109, magnetic field MF inmaterial FM decreases but does not disappear completely. The remainingmagnetic field MF is governed by the retentivity, or residual magnetism,of material FM, shown as B_r in FIG. 3. This residual field MF can bedetrimental to the operation of some devices. For example as furtherdescribed below, residual field MF can prevent proper operation ofactuator 107.

Attenuating (continuously decreasing) alternating current currents EC1and EC2 through coil 109 create a constantly reversing flux field inferromagnetic material FM. In FIG. 2, the direction (direction D1) ofmagnetic field MF corresponds to current EC1. The attenuating andreversing flux fields randomize the magnetic orientation of material FM,removing residual magnetization in material FM. As noted above, whenpower is removed from coil 109, oscillating circuit OC oscillates andrandomizes the magnetic domains in material FM as energy in the form ofheat generated by the electrical resistance of coil 109 and currents EC1and EC2 passing through coil 109. Capacitor 112 can be selected togenerate a desired frequency of oscillations for a particular size ofcoil 109, to completely remove the residual magnetism noted above.

FIG. 4 is a graph of electrical current through coil 109 (current EC1and EC2 on the Y axis) and time (X axis) showing oscillating waveformOW. The following should be viewed in light of FIGS. 1 through 4. Whenoscillating circuit OC begins oscillating: coil 109 attempts to maintaina constant current through coil 109, while capacitor 112 attempts tomaintain a constant voltage Vc. For example, coil 109 pushes current EC1in direction D1, thus inducing a voltage drop across coil 109. Capacitor112 opposes the voltage drop by driving current EC2 in oppositedirection D2. The oscillating push and pull of currents EC1 and EC2between coil 109 and capacitor 112 continues until power in coil 109 andcapacitor 112 is dissipated as heat through the electrical resistance ofcoil 109.

No control or intervention is required to generate the waveform in FIG.4 once switches 113 and 114 are opened. That is, the oscillating pushand pull of currents EC1 and EC2 between coil 109 and capacitor 112begins when switch 113 is opened and continues without further activecontrol. The electrical resistance of coil 109 determines the decay timeof the oscillations in FIG. 4. Increasing the resistance increases thespeed at which waveform OW decreases to zero. In cases in which theresistance and inductance of coil 109 are fixed to accommodate otherdesign considerations of actuator 107, capacitance values for capacitor112 are selectable to achieve a desired oscillation frequency and decaytime. Thus, circuit 108 has the modularity for removing residualmagnetism in many sizes of motor or solenoid systems.

In an example embodiment, switch 113 is an n-type transistor (either annpn or n-MOSFET). In the discussion that follows, ‘transistor 113’ isused in place of ‘switch 113.’ Applying control voltage CV1 from controlunit CU (part of the vehicle or system including actuator 107 andcircuit 108) to gate G1 of transistor 113 switches transistor 113 on,creating a current path from coil 109 to ground EG. The current pathenables current to flow through coil 109, creating magnetic field MF.Removing control voltage CV1 from gate G1 switches off transistor 113,disrupting the current path through coil 109 to ground EG.

Thus, when switched off, transistor 113 isolates coil 109/capacitor 112and oscillating circuit OC from ground EG. Once isolated from ground EG,oscillating circuit OC begins oscillating as described above to createcurrents EC1 and EC2. Thus, there is no loss of the power in oscillatingcircuit OC through bleeding into ground EG. That is, a maximum amount ofthe power in oscillating circuit OC is available for creating theattenuating and reversing flux fields noted above.

In an example embodiment, switch 114 is a p-type transistor (pnp orPMOS). In the discussion that follows, ‘transistor 114’ is used in placeof ‘switch 114.’ By switching transistor 114 on, current flow throughcoil 109 is enabled as transistor 114 is switched on. By switching offtransistor 114, power source EPS is isolated from coil 109, providingadditional circuit protection and isolation when transistor 113 isswitched off. In an example embodiment, n-type transistor 115 is wiredto gate G2 of transistor 114 to enable easier switching of transistor114. In general, control voltages, such as CV1, are less than voltageVs. Transistor 115 is switched on by control voltage CV2, at gate G3 oftransistor 115, less than voltage Vs from source EPS. When voltage atgate G2 equals voltage Vs, transistor 114 is switched off.

As noted above, to switch coil 109 on, transistor 114 is switched on. Toswitch transistor 114 on, control voltage CV2 is applied to gate G3,switching transistor 115 on, creating a ground path from gate G2, suchthat voltage at gate G2 is less than voltage Vs. Removing controlvoltage CV2 from gate G3 switches transistor 115 off, isolating gate G2from ground and applying voltage Vs to gate G2 to switch transistor 114off. In an example embodiment, resistor R1 with value R is added tocircuit 108 to provide a voltage drop path.

FIG. 5 is an exploded view of example wedge clutch 100 with residualmagnetism attenuation shown in FIG. 1.

FIG. 6 is a front view of wedge clutch 100 with residual magnetismattenuation shown in FIG. 5.

FIG. 7 is a cross-sectional view of electromagnetic actuator 107A shownin FIG. 5. The following should be viewed in light of FIGS. 1 through 7.Wedge clutch 100 includes: axis of rotation AR; outer race 102; innerrace 104; wedge plates 106A and 106B; and electromagnetic actuator 107A.Wedge plates 106A and 106B are radially disposed between inner race 104and outer race 102. In an example embodiment, wedge plates 106A and 106Bincludes slots SL1 extending radially inwardly from radially outercircumference ROC and slots SL2 extending radially outwardly fromradially inner circumference RIC. Attenuating circuit 108 for actuator107A is schematically presented in FIG. 5. An actual configuration andposition of circuit 108 is dependent at least in part upon theconfiguration of the electrical system powering actuator 107A. Ingeneral, a reference character “[digit][digit][digit][letter]”designates a specific example of an element labeled as “[digit][digit][digit].” For example, wedge plate 106A is a specific examplefrom among wedge plates 106.

In the example of FIG. 5, electromagnetic actuator 107A includes coil109; bobbin 115; coil core piece 110A; and coil core piece 110B. Coilcore piece 110A includes: end 111A disposed within coil 109; and end105A connected to wedge plates 106A and 106B. Coil core piece 110Bincludes: end 111B disposed within coil 109; and end 105B connected towedge plates 106A and 106B. To accommodate the radially inwarddisplacement and radial contraction of wedge plates 106A and 106Bdescribed below, ends 111A and 111B are separated by air gap 118.

In the example of FIG. 5, inner race 104 is arranged to receiverotational torque. In a first locked mode of wedge clutch 100, innerrace 104, wedge plates 106A and 106B, and outer race 102 arenon-rotatably connected for rotation of inner race 104 incircumferential direction CD1. In a first free-wheel mode of wedgeclutch 100, inner race 104 is rotatable, with respect to the outer race102, in circumferential direction CD1. By “non-rotatably connected”components, we mean that: the components are connected so that wheneverone of the components rotates, all the components rotate; and relativerotation between the components is not possible. Radial and/or axialmovement of non-rotatably connected components with respect to eachother is possible, but not required.

To transition from the first locked mode to the first free-wheel mode,electromagnetic actuator 107A is arranged to be energized to: draw ends111A and 111B toward each other; displace wedge plates 106A and 106Bradially inwardly; and radially contract wedge plates 106A and 1068. Totransition from the first free-wheel mode to the first locked mode:electromagnetic actuator 107A is arranged to be de-energized; and wedgeplates 106A and 106B are arranged to expand radially outwardly toinitiate or increase frictional contact between wedge plates 106A and1068 and outer race 102. For example, wedge plates 106A and 106B arepreloaded with a radially outwardly expanding force that is overcome byelectromagnetic actuator 107A to transition to the first free-wheelmode, and which results in the radial expansion characterizing thetransition to the first locked mode.

FIG. 8 is a front view of wedge plate 106A of wedge clutch 100 withresidual magnetism attenuation shown in FIG. 5. The following should beviewed in light of FIGS. 1 through 8. Wedge plate 106A includes:circumferential end 120; and circumferential end 122. Wedge plate 106Ais discontinuous between end 120 and end 122. For example, ends 120 and122 are separated by gap 124 in circumferential direction CD1. End 105Aof coil core piece 110A of electromagnetic actuator 107A is fixedlyconnected to circumferential end 120. End 105B of coil core piece 1108of electromagnetic actuator 107A is fixedly connected to circumferentialend 128.

FIG. 9 is a front view of wedge plate 106B of wedge clutch 100 withresidual magnetism attenuation shown in FIG. 5. The following should beviewed in light of FIGS. 1 through 9. Wedge plate 106B includes:circumferential end 126; and circumferential end 128. Wedge plate 106Bis discontinuous between end 126 and end 128. For example, ends 126 and128 are separated by gap 130 in circumferential direction CD1. End 105Aof coil core piece 110A of electromagnetic actuator 107A is fixedlyconnected to circumferential end 126. End 105B of coil core piece 110Bof electromagnetic actuator 107A is fixedly connected to circumferentialend 128. In an example embodiment, end 105A of coil core piece 110A isfixedly connected to circumferential ends 120 and 126 with a bolt 132and end 105B of coil core piece 110B is fixedly connected tocircumferential ends 122 and 128 with a bolt 132. However, it should beunderstood that any means known in the art can be used to fixedlyconnect coil core pieces 110A and 110B to wedge plates 106A and 106B.

To transition from the first locked mode to the first free-wheel mode,electromagnetic actuator 107A is arranged to be energized to: bringcircumferential end 120 and circumferential end 122 toward each incircumferential direction CD1 or circumferential direction CD2, oppositecircumferential direction CD1; and bring circumferential end 126 andcircumferential end 128 toward each in circumferential direction CD1 orcircumferential direction CD2. Stated otherwise, electromagneticactuator 107A is arranged to be energized to decrease gaps 124 and 130.

FIG. 10 is a front view of inner races of wedge clutch 100 with residualmagnetism attenuation shown FIG. 5. The following should be viewed inlight of FIGS. 1 through 10. Wedge plate 106A includes ramps 134. Wedgeplate 106B includes ramps 136. Inner race 104 includes ramps 138. Eachramp 134 is in contact with a respective ramp 138. Each ramp 136 is incontact with a respective ramp 138. Each ramp 134, each ramp 136, andeach ramp 138 slope radially inwardly in circumferential direction CD1.To transition from the first locked mode to the first free-wheel mode,electromagnetic actuator 107A is arranged to: slide at least one ramp134 radially inwardly along at least one ramp 138; and slide at leastone ramp 136 radially inwardly along at least one ramp 138.

FIG. 11 is a back view of wedge plate 106C of wedge clutch 100 withresidual magnetism attenuation shown in FIG. 5.

FIG. 12 is a back view of wedge plate 106D of wedge clutch 100 withresidual magnetism attenuation shown FIG. 5. The following should beviewed in light of FIGS. 1 through 12. In an example embodiment, wedgeclutch 100 includes: inner race 140 non-rotatably connected to innerrace 104 with bolts 142; wedge plates 106C and 106D; and electromagneticactuator 107B. Any means known in the art can be used to non-rotatablyconnect inner races 104 and 140. In an example embodiment (not shown),inner races 104 and 140 are a single monolithic structure. Wedge plates106C and 106D are radially disposed between inner race 140 and outerrace 102. The discussion for actuator 107A is applicable to actuator1078 unless noted otherwise.

In an example embodiment, wedge plates 106C and 106D includes slots SL1extending radially inwardly from radially outer circumference ROC andslots SL2 extending radially outwardly from radially inner circumferenceRIC. Ends 105A and 1058 of actuator 107B are connected to wedge plates106C and 106D.

In a second locked mode of wedge clutch 100, inner race 140, wedgeplates 106C and 106D, and outer race 102 are non-rotatably connected forrotation of inner race 140 in circumferential direction CD2. In a secondfree-wheel mode of wedge clutch 100, inner race 140 is rotatable, withrespect to outer race 102, in circumferential direction CD2.

To transition from the second locked mode to the second free-wheel mode,electromagnetic actuator 107B is arranged to be energized to: draw ends111A and 111B of actuator 1078 toward each other; displace wedge plates106C and 106D radially inwardly; and radially contract wedge plates 106Cand 106D. To transition from the second free-wheel mode to the secondlocked mode: electromagnetic actuator 107 is arranged to bede-energized; and wedge plates 106C and 106D are arranged to expandradially outwardly to initiate or increase frictional contact betweenwedge plates 106C and 106D and outer race 102. For example, wedge plates106C and 106D are preloaded with a radially outwardly expanding forcethat is overcome by electromagnetic actuator 107B to transition to thesecond free-wheel mode, and which results in the radial expansioncharacterizing the transition to the second locked mode.

Wedge plate 106C includes: circumferential end 144; and circumferentialend 146. Wedge plate 106C is discontinuous between end 144 and end 146.For example, ends 144 and 146 are separated by gap 148 incircumferential direction CD1. End 105A of coil core piece 110A ofelectromagnetic actuator 107B is fixedly connected to circumferentialend 144. End 105B of coil core piece 1108B of electromagnetic actuator107B is fixedly connected to circumferential end 146. In an exampleembodiment, end 105A is fixedly connected to circumferential end 144with bolt 132 and end 105B is fixedly connected to circumferential end146 with bolt 132. However, it should be understood that any means knownin the art can be used to fixedly connect end 105A of coil core piece110A to circumferential end 144 and to fixedly connect end 105B of coilcore piece 110B to circumferential end 146.

Wedge plate 106D includes: circumferential end 150; and circumferentialend 152. Wedge plate 106D is discontinuous between end 150 and end 152.For example, ends 150 and 152 are separated by gap 154 incircumferential direction CD1. End 105A of coil core piece 110A ofelectromagnetic actuator 107B is fixedly connected to circumferentialend 150. End 105B of coil core piece 110B of electromagnetic actuator107B is fixedly connected to circumferential end 152. In an exampleembodiment, end 105A of coil core piece 110A is fixedly connected tocircumferential end 150 with bolt 132 and end 105B of coil core piece110B is fixedly connected to circumferential end 152 with bolt 132.However, it should be understood that any means known in the art can beused to fixedly connect end 105A to circumferential end 150 and tofixedly connect end 105B to circumferential end 152.

To transition from the second locked mode to the second free-wheel mode,electromagnetic actuator 107B is arranged to be energized to: bringcircumferential end 144 and circumferential end 146 toward each incircumferential direction CD1 or circumferential direction CD2; andbring circumferential end 150 and circumferential end 152 toward each incircumferential direction CD1 or circumferential direction CD2. Statedotherwise, electromagnetic actuator 107B is arranged to be energized todecrease gaps 148 and 154.

Wedge plate 106C includes ramps 156, wedge plate 106D includes ramps158, and inner race 140 includes ramps 160. Each ramp 156 is in contactwith a respective ramp 160. Each ramp 158 is in contact with arespective ramp 160. Each ramp 156, each ramp 158, and each ramp 160,slope radially inwardly in circumferential direction CD2. To transitionfrom the second locked mode to the second free-wheel mode,electromagnetic actuator 107B is arranged to: slide at least one ramp156 radially inwardly along at least one ramp 160; and slide at leastone ramp 158 radially inwardly along at least one ramp 160.

FIG. 13 is a cross-sectional view generally along line 13-13 in FIG. 6.The following should be viewed in light of FIGS. 1 through 13. In anexample embodiment: wedge plate 106A includes chamfer 162; wedge plate106B includes chamfer 164; and inner race 104 includes groove 166.Chamfers 162 and 164 are disposed at least partly in groove 166. In anexample embodiment: wedge plate 106C includes chamfer 168; wedge plate106D includes chamfer 170; and inner race 140 includes groove 172.Chamfers 168 and 170 are disposed at least partly in groove 172. In anexample embodiment: inner race 104 includes slot 174, in which actuator107A is located; and inner race 140 includes slot 176, in which actuator107B is located. Electrical power is supplied to electromagneticactuators 107A and 107B by any means known in the art. In an exampleembodiment, clutch 100 includes slip ring retainer 178 and slip ring 180for supplying electrical power to electromagnetic actuators 107A and107B.

FIG. 14 is an exploded view of example wedge clutch 220 with residualmagnetism attenuation. Wedge clutch 220 includes: axis of rotation AR;outer race 222; inner race 224; wedge plates 106E and 106F; andelectromagnetic actuator 107C including attenuating circuit 108. Wedgeplates 106E and 106F are radially disposed between inner race 224 andouter race 222. In the example of FIG. 14, inner race 224 is arranged toreceive rotational torque. The discussion for electromagnetic actuator107A is applicable to electromagnetic actuator 107C in FIG. 14.Attenuating circuit 108 for actuator 107C is schematically presented inFIG. 14. An actual configuration and position of circuit 108 isdependent at least in part upon the configuration of the electricalsystem powering actuator 107C.

FIG. 15 is a front view of wedge clutch 220 with residual magnetismattenuation shown in FIG. 14;

FIG. 16 is a front view of wedge plate 106E of wedge clutch 220 withresidual magnetism attenuation shown FIG. 14. The following should beviewed in light of FIGS. 14 through 16. In an example embodiment, wedgeplates 106E and 106F includes slots SL1 extending radially inwardly fromradially outer circumference ROC and slots SL2 extending radiallyoutwardly from radially inner circumference RIC. End 105A of actuator107C is connected to wedge plates 106E and 106F. End 105B of actuator107C is connected to wedge plates 106E and 106F.

In a locked mode of wedge clutch 220, inner race 224, wedge plates 106Eand 106F, and outer race 222 are non-rotatably connected for rotation ofinner race 224 in circumferential direction CD1 or in circumferentialdirection CD2. In a free-wheel mode of wedge clutch 220, inner race 224is rotatable, with respect to outer race 222 in circumferentialdirection CD1 or in circumferential direction CD2.

To transition from the locked mode to the free-wheel mode,electromagnetic actuator 107C is arranged to be energized to: draw ends111A and 111B of actuator 107C toward each other; displace wedge plates106E and 106F radially inwardly; and radially contract wedge plates 106Eand 106F. To transition from the free-wheel mode to the locked mode:electromagnetic actuator 107C is arranged to be de-energized; and wedgeplates 106E and 106F are arranged to expand radially outwardly toinitiate or increase frictional contact between wedge plates 106E and106F and outer race 222. For example, wedge plates 106E and 106F arepreloaded with a radially outwardly expanding force that is overcome byelectromagnetic actuator 107C to transition to the free-wheel mode, andwhich results in the radial expansion characterizing the transition tothe locked mode.

Wedge plate 106E includes: circumferential end 226; and circumferentialend 228. Wedge plate 106E is discontinuous between end 226 and end 228.For example, ends 226 and 228 are separated by gap 230 incircumferential direction CD1. End 105A of coil core piece 110A isfixedly connected to circumferential end 226. End 105B of coil corepiece 110B is fixedly connected to circumferential end 228.

FIG. 17 is a front view of wedge plate 106F of electromagneticselectable wedge clutch 220 shown in FIG. 14. The following should beviewed in light of FIGS. 14 through 17. Wedge plate 106F includes:circumferential end 232; and circumferential end 234. Wedge plate 106Fis discontinuous between end 232 and end 234. For example, ends 232 and234 are separated by gap 236 in circumferential direction CD1. End 105Aof coil core piece 110A is fixedly connected to circumferential end 232.End 105B of coil core piece 110B is fixedly connected to circumferentialend 234. In an example embodiment, end 105A of coil core piece 110A isfixedly connected to circumferential ends 226 and 232 with a bolt 237and end 105B of coil core piece 110B is fixedly connected tocircumferential ends 228 and 234 with a bolt 237. However, it should beunderstood that any means known in the art can be used to fixedlyconnect coil core pieces 110A and 110B to wedge plates 106E and 106F.

To transition from the locked mode to the free-wheel mode,electromagnetic actuator 107C is arranged to be energized to: bringcircumferential end 226 and circumferential end 228 toward each incircumferential direction CD1 or circumferential direction CD2; andbring circumferential end 232 and circumferential end 234 toward each incircumferential direction CD1 or circumferential direction CD2. Statedotherwise, electromagnetic actuator 107C is arranged to be energized todecrease gaps 230 and 236.

FIG. 18 is a front view of inner race 224 of wedge clutch 220 withresidual magnetism attenuation shown in FIG. 14. The following should beviewed in light of FIGS. 14 through 18. Wedge plate 106E includes ramps238 and 239. Wedge plate 106F includes ramps 240 and 241. Inner race 224includes ramps 242 and 243. Each ramp 238 is in contact with arespective ramp 242. Each ramp 239 is in contact with a respective ramp243. Each ramp 240 is in contact with a respective ramp 242. Each ramps241 is in contact with a respective ramp 243. Ramps 238, 240, and 242slope radially inwardly in circumferential direction CD2. Ramps 239,241, and 243 slope radially inwardly in circumferential direction CD1.

FIG. 19 is a cross-sectional view generally along line 19-19 in FIG. 15.The following should be viewed in light of FIGS. 14 through 19. In anexample embodiment: wedge plate 106E includes chamfer 244; wedge plate106F includes chamfer 246; and inner race 224 includes groove 248.Chamfers 244 and 246 are disposed at least partly in groove 248. In anexample embodiment: inner race 224 includes slot 250, in which actuator107C is located. Electrical power is supplied to actuator 107C by anymeans known in the art. In an example embodiment, clutch 220 includesslip ring retainer 252 and slip ring 254 for supplying electrical powerto actuator 107C.

It should be understood that clutches 100 and 220 are not limited to theexample embodiments shown and described. For example, thecircumferential directions in which respective ramps slope can bereversed. For example, different numbers of ramps for wedge plates andinner races are possible.

FIG. 20 is a front view of example wedge clutch 300 with residualmagnetism attenuation.

FIG. 21 is an enlarged view of region 21 in FIG. 20. The followingshould be viewed in light of FIGS. 20 and 21. Wedge clutch 300 includes:outer race 302; inner race 304; wedge plate 306 radially disposedbetween inner race 304 and outer race 302; and electromagnetic actuator308 including attenuating circuit 108. Electromagnetic actuator 308 isembedded in wedge plate 306 and includes coil 310 and coil core piece312 with: end 314 fixedly connected to wedge plate 306; and end 316enclosed by coil 310. Coil 310 is wrapped about fingers 318 formed bywedge plate 306. That is, wedge plate 306 forms a portion of actuator308. Attenuating circuit 108 for actuator 308 is schematically presentedin FIG. 21. An actual configuration and position of circuit 108 isdependent at least in part upon the configuration of the electricalsystem powering actuator 308. Wedge plate 306 is analogous toferromagnetic material FM discussed in FIGS. 1 through 4. Actuator 308has only one single coil core piece 310.

In the configuration of FIG. 20, inner race 304 is arranged to receiverotational torque. Wedge plate 306 includes ramps 320 and 322. Innerrace 304 includes: ramps 324, engaged with ramps 320; and ramps 326engaged with ramps 322. The discussion for FIGS. 14 through 19 regardingwedge plate 106E, ramps 238, 239, 242, and 243 is applicable to wedgeplate 306, and ramps 320, 322, 324, and 326, respectively.

The discussion for FIGS. 14 through 19 regarding operation of clutch 220is generally applicable to clutch 300. Like clutch 220, clutch 300 has afree-wheel operating mode and a locked operating mode. To transitionfrom the locked mode to the free-wheel mode, actuator 308 is energizedto displace coil core piece 310 in circumferential direction CD1 todisplace wedge plate 306 radially inwardly and radially contract wedgeplate 306 so that inner race 304 and wedge plate 306 are rotatable withrespect to outer race 302. To transition from the free-wheel mode to thelocked mode, actuator 308 is de-energized and wedge plate 306 displacesradially outwardly to initiate or increase frictional contact betweenwedge plate 306 and outer race 302 to non-rotatably connect inner race304, wedge plate 306, and outer race 302.

As noted above, when electrical power is removed from coil 109, magneticfield MF in material FM decreases but does not disappear completely. Theresidual field MF can be detrimental to the operation of clutches 100and 200. For example, for clutch 100 and actuator 107A, a residual fieldMF can continue to urge ends 111A and 111B toward each other during thetransition from the first free-wheel mode to the first locked mode. As aresult, wedge plates 106A and 106B may not expand and displace radiallyoutwardly to engage outer race 102 with sufficient frictional force tocause wedge plates 106A and 106B to rotate with outer race 102 and withrespect to inner race 104. Without the preceding rotations, thetransition to the locked mode does not occur. The residual field MFcould prevent the transition from the first free-wheel mode to the firstlocked mode, or could delay the transition from the first free-wheelmode to the first locked mode, either of which would be detrimental tooperation of clutch 100 and any device, such as a power train, includingclutch 100.

Attenuating circuit 108 for actuator 107A eliminates a residual field MFin actuator 107A as described above in the discussion for FIGS. 1through 4. Thus, circuit 108 in actuator 107A eliminates potentialproblems noted above regarding operation of clutch 100. The precedingdiscussion regarding a residual field MF in actuator 107A is applicableto actuator 107B and 107C.

When electrical power is removed from coil 310, a magnetic field inwedge plate 306 decreases but does not disappear completely. A residualmagnetic field can be detrimental to the operation of clutch 300. Forexample, a residual magnetic field can continue to urge end 316 indirection CD1 during the transition from the free-wheel mode to thelocked mode. As a result, wedge plate 306 may not expand and displaceradially outwardly to engage outer race 302 with sufficient frictionalforce to cause wedge plate 306 to rotate with outer race 302 and withrespect to inner race 304. Without the preceding rotations, thetransition to the locked mode does not occur. The residual magneticfield could prevent the transition from the free-wheel mode to thelocked mode, or could delay the transition from the free-wheel mode tothe locked mode, either of which would be detrimental to operation ofclutch 300 and any device, such as a power train, including clutch 300.

Attenuating circuit 108 for actuator 308 eliminates a residual magneticfield in wedge plate 308 as described above for actuator 107A. Thus,circuit 108 in actuator 308 eliminates potential problems noted aboveregarding operation of clutch 300.

FIG. 22 is a schematic cross-sectional view of pump 10, with residualmagnetism attenuation.

FIG. 23 is an exploded view of pump 10 shown in FIG. 22.

FIG. 24 is a front view of a stator, a rotor and a swash plate of thepump shown in FIG. 22. The following should be viewed in light of FIGS.22 through 24. Pump 10 includes: fluid inlet section 12 of a housing;fluid outlet section 14 of the housing; stator 16 axially between fluidinlet section 12 and fluid outlet section 14; and rotor 18 axiallybetween fluid inlet section 12 and fluid outlet section 14. Rotor 18 andstator 16 define fluid flow space 20 radially therebetween. Pump 10 alsoincludes: movable inlet guide, or swash plate, 22 configured for guidingfluid flow from fluid inlet section 12 into fluid flow space 20; andmovable outlet guide, for swash plate, 24 configured for guiding fluidflow from fluid flow space 20 into fluid outlet section 14.

Stator 16 is provided with electrical windings 26 for generatingelectromagnetic forces in stator 16 to urge rotor 18 toward stator 16such that rotor 18 rotates inside of stator 16. In an exampleembodiment, stator 16 is provided with six electrical windings 26, butin other embodiments, stator 16 may be provided with any other amountsof windings 26 greater than three. Windings 26 are each wrapped aroundone of legs 28 of stator 16. Stator 16 includes cylindrical ring 30defining an outer circumference of stator 16, with each leg 28protruding radially inward from cylindrical ring 30. Each legs 28includes base 32 extending radially inward from an inner circumferenceof cylindrical ring 30, two branches 34 extending circumferentially froma radially inner end of base 32 in opposite circumferential directions,and rounded radially innermost tip 36 protruding radially inward frombranches 34. Windings 26 are wrapped around base 32 and held radially inplace by the inner circumferential surface of cylindrical ring 30 andthe outer circumferential surfaces of branches 34. In an exampleembodiment (not shown) insulation layers are provided over windings 26to insulate windings from fluid flow space 20.

Rotor 18 is substantially star shaped and includes radially outwardlyextending protrusions 38. In an example embodiment, rotor 18 includesfive protrusions 38. However, rotor 18 may include other amounts ofprotrusions 38, with the amount of protrusions 38 being one less thanthe number of windings 26. Protrusions 38 each include radiallyoutermost rounded tip 40. Rotor 18 is configured such that duringrotation, protrusions 38 sequentially enter into slots 42 betweenprotrusions 38 to continuously vary the configuration of fluid flowspace 20.

When an electric current is sent through any one of windings 26 amagnetic field is created which pulls rotor 18 toward that winding 26 inorder to complete a magnetic circuit formed by legs 28 of the stator. Asrotor 18 moves toward the winding 26, rotor 18 displaces fluid, withwhich fluid flow space 20 between rotor 18 and stator 16 is filled,creating pressure. The movement of rotor 18 within stator 16 separatesfluid flow space 20 into portion 20 a pressurized to force fluid out ofoutlet section 14 and a portion 20 b that forms a vacuum to draw fluidinto fluid flow space 20 from inlet section 12. As rotor 18 rotateswithin stator 16, the locations of portion 20 a and portion 20 b rotateabout a center axis 44, with portion 20 a being oriented on the oppositeradial side of rotor 18 as portion 20 b during the rotation.

In order to properly align inlet section 12 with portion 20 b whileisolating inlet section 12 from portion 20 a, pump 10 includes a movableinlet guide in the form of inlet swash plate 22 upstream from rotor 18.In order to properly align outlet section 14 with portion 20 a, whileisolating inlet section 12 from second portion 20 b, pump 10 includes amovable outlet guide in the form of an outlet swash plate 24 downstreamfrom rotor 18. Inlet swash plate 22 is configured to move to alignportion 20 a of fluid flow space 20 with fluid inlet section 12 andoutlet swash plate 24 is configured to move to align portion 20 b offluid flow space 20 with the fluid outlet section 14. More specifically,swash plates 22 and 24 non-rotatably fixed to rotor 18 such that swashplates 22 and 24 are configured to rotate about center axis 44 in theopposite direction as rotor 18. Swash plates 22 and 24 arecircumferentially offset from each other and on diametrically oppositeradial sides of center axis 44 when viewed cross-sectionally in theaxial direction.

FIG. 24 illustrates an axially facing cross-sectional view stator 16,rotor 18, inlet swash plate 22 and outlet swash plate 24 from the fluidinlet side of pump 10. As shown in FIG. 24, swash plates 22 and 24 arearranged in a complementary manner to form a circle, with each swashplate 22 or 24 having a semi-circular cross section as define by theouter circumference of each swash plate 22 or 24. Rotor 18 rotates aboutaxis 44 in a rotational direction D3 while swash plates 22 and 24 rotateabout axis 44 in rotational direction D4.

Fluid from the high pressure side, i.e., portion 20 b, is pushed pastoutlet swash plate 24 and out outlet section 14. At the same time, fluidis drawn in through inlet section 12 past inlet swash plate 22, fillingthe vacuum side, i.e., portion 20 a of rotor 18. When rotor 18 istravelling toward a particular winding 26, the next winding 26 isenergized and the process continues, rolling rotor 18 around the insideof stator 16 and pumping fluid from inlet section 12 to outlet section14. Because the high and low pressure sides are continuously movingaround stator 16, swash plates 22 and 24 are used to align the highpressure side with the outlet and the low pressure side with the inlet.Swash plates 22 and 24 are centered on lips 12 a and 12 b of inletsection 12 and lips 14 a and 14 b of outlet section 14, respectively,and are driven by a pin 50 in rotor 18. This causes swash plates 22 and24 to rotate in the opposite direction that rotor 18 is rolling,maintaining alignment with the correct pressures.

As noted above, for an electric reluctance motor, such as is embodied bypump 10, windings 26 energized and de-energized in sequence to createrotating magnetic fields that rotate rotor 18. However, also as notedabove, residual magnetism can remain in stator 16 when a winding 26 isde-energized. Specifically, when an electric current is sent through anyone of windings 26 a magnetic field is created which pulls rotor 18toward that winding 26 in order to complete a magnetic circuit formed bylegs 28 of the stator. Thus, when the particular winding 26 noted aboveis energized, a magnetic field is created through the leg 28 about whichthe particular winding is wrapped. When the next winding 26 isenergized, the particular winding 26 is de-energized. The magnetic fieldcreated by the particular winding 26 is diminished when the particularwinding 26 is de-energized; however, residual magnetism may remain inthe leg 28 about which the particular winding is wrapped. As the nextwinding 26 is energized to rotate the rotor, the residual magnetismresists the rotation of the rotor, interfering with the operation ofpump 10 and reducing the efficiency of pump 10.

However, a circuit 108, wired in parallel with a winding 26 reduces orremoves the residual magnetism from the winding 26. For example, eachwinding 26 is analogous to coil 109 discussed in FIGS. 1 through 4 andeach leg 28 is analogous to ferromagnetic material FM discussed in FIGS.1 through 4. An attenuating circuit 108 is schematically presented foronly two winding 26 in FIG. 22. However, it should be understood that anattenuating circuit can be wired to every winding 26 in pump 10. Anactual configuration and position of circuit(s) 108 is dependent atleast in part upon the configuration of the electrical system poweringwindings 26.

Swash plate 22 and 24 are fixed together and to rotor 18 by pin 50extending axially through rotor 18 and defining center axis 44. Rotor 18is mounted eccentrically on pin 50 such that rotor 18 rotateseccentrically about center axis 44 during operation of pump 10. Inletswash plate 22 is mounted on a first axial end of pin 50 and swash plate24 is mounted on a second axial end of pin 50. Inlet section 12 includesannular groove 52 for guiding the rotation of swash plate 22 and outletsection 14 similarly includes annular groove 54 for guiding the rotationof swash plate 24. The rotation of rotor 18 causes swash plates 22 and24 to slide in annular grooves 52 and 54, respectively, such that theouter circumference of each swash plate 22 or 24 movescircumferentially, but does not move radially, while pin 50 and centeraxis 44 follow a circular path due to the eccentric placement of pin 50on swash plates 22 and 24.

Swash plates 22 and 24 each include connecting portion 22 a and 24 a anda guide portion 22 b and 24 b eccentrically fixed to the respectiveconnecting portion 22 a and 24 a. Guide portions 22 b and 24 b eachinclude a respective outer circumferential surface 22 c and 24 c, arespective longer radially extending surface 22 d and 24 d extendingradially from the respective connecting portion 22 a and 24 a to a firstedge of respective outer circumferential surface 22 c and 24 c and shortradially extending surface 22 e and 24 e extending radially from therespective connecting portion 22 a and 24 a to a second edge of therespective outer circumferential surface 22 c and 24 c.

Each guide portion 22 b and 24 b also includes an axially protrudingarc-shaped lip 22 f and 24 f configured for sliding in annular grooves52 and 54, respectively. Outer circumferential surfaces 22 c and 24 c oflips 22 f and 24 f slide along outer circumferential surface 52 a and 54a of grooves 52 and 54, respectively, and inner circumferential surfaces22 g and 24 g of lips 22 f and 24 f slide along an inner circumferentialsurface 52 b and 54 b of grooves 52 and 54, respectively. Innercircumferential surface 52 b of annular groove 52 is defined by annularinner circumferential lip 12 a of inlet section 12 and outercircumferential surface 52 a of annular groove 52 is defined by annularouter circumferential lip 12 b of inlet section 12. Similarly, innercircumferential surface 54 b of annular groove 54 is defined by annularinner circumferential lip 14 a of outlet section 14 and outercircumferential surface 54 a of annular groove 54 is defined by anannular outer circumferential lip 14 b of outlet section 14.

Inlet swash plate 22 is axially in contact with a radially extendinginlet side surface 18 a of rotor 18 and an inner portion of a radiallyextending inlet side surface 16 a of stator 16 and outlet swash plate 24is axially in contact with a radially extending outlet side surface 18 bof rotor 18 and an inner portion of a radially extending outlet sidesurface 16 b of stator 16. Annular outer circumferential lip 12 b ofinlet section 12 also contacts radially extending inlet side surface 16a of stator 16 and annular outer circumferential lip 14 b of outletsection 14 contacts radially extending outlet side surface 16 b ofstator 16. Inlet and outlet sections 12 and 14, are provided withflanges 62 and 64, respectively, which in this embodiment aretriangular, that include through holes for receiving fasteners forclamping sections 12 and 14 axially together onto stator 16. Protrudingaxially outward from flanges 62 and 64, respectively, inlet and outletsections 12 and 14 include respective male threaded tubes 68 and 70 forconnecting to corresponding female threaded components.

Pump 10 also includes controller 56 configured to control the flow ofthe current through electrical windings 26 to rotate rotor 18. In anexample embodiment, controller 56 is in the form of transistors on acontrol board for electrically commutating and controlling pump 10.Alternately, the controller can be remote and connected to windings 26by wires.

In the example of FIGS. 20 through 22, pump 10 is a gerotor pump;however, in other embodiments, a similar construction may be made withother pump types, including an internal gear pump or a vane pump.

It will be appreciated that various of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be desirablycombined into many other different systems or applications. Variouspresently unforeseen or unanticipated alternatives, modifications,variations, or improvements therein may be subsequently made by thoseskilled in the art which are also intended to be encompassed by thefollowing claims.

LIST OF REFERENCE CHARACTERS

-   AR axis of rotation-   B magnetic flux density-   B_sat saturation point-   B_r residual magnetism-   CU control unit-   CV1 control voltage-   CV2 control voltage-   D1 direction-   D2 direction-   D3 direction-   D4 direction-   EC1 electrical current-   EC2 electrical current-   EG electrical ground-   EPS electrical power source-   FM1 ferromagnetic material-   G1 gate-   G2 gate-   G3 gate-   H magnetic field strength-   MF magnetic field-   OC oscillating circuit-   OW oscillating waveform-   R resistor value-   R1 resistor-   RIC radially inner circumference-   ROC radially outer circumference-   SL1 slot-   SL2 slot-   Vc capacitor voltage-   Vs source voltage-   10 pump-   12 fluid inlet-   12 a lip, fluid inlet-   12 b lip, fluid inlet-   14 fluid outlet-   14 a lip, fluid inlet-   14 b lip, fluid inlet-   16 stator-   16 a surface, stator-   16 b surface, stator-   18 rotor-   18 a surface, rotor-   18 b surface, rotor-   20 fluid flow space-   20 a portion, fluid flow space-   20 b portion, fluid flow space-   22 inlet guide-   22 a portion, inlet guide-   22 b portion, inlet guide-   22 c portion, inlet guide-   22 d portion, inlet guide-   22 e portion, inlet guide-   22 f portion, inlet guide-   22 g portion, inlet guide-   24 outlet guide-   24 a portion, outlet guide-   24 b portion, outlet guide-   24 c portion, outlet guide-   24 d portion, outlet guide-   24 e portion, outlet guide-   24 f portion, outlet guide-   24 g portion, outlet guide-   26 windings-   28 leg, stator-   30 ring, stator-   32 base, leg-   34 branches, leg-   36 tip, leg-   38 protrusion-   40 tip-   42 slot-   44 center axis-   50 pin-   52 groove, inlet section-   52 a surface groove, inlet section-   52 b surface groove, inlet section-   54 groove, outlet section-   54 a surface groove, outlet section-   54 b surface groove, outlet section-   56 controller-   62 flange, inlet-   64 flange, outlet-   68 tube-   70 tube-   100 wedge plate clutch-   102 outer race-   104 inner race-   105 end, coil core piece-   105A end, coil core piece-   105B end, coil core piece-   106 wedge plate-   106A wedge plate-   106B wedge plate-   106C wedge plate-   106D wedge plate-   106E wedge plate-   106F wedge plate-   107 electromagnetic actuator-   107A electromagnetic actuator-   107B electromagnetic actuator-   107C electromagnetic actuator-   108 attenuating circuit-   109 coil-   110 coil core piece-   110A coil core piece-   110B coil core piece-   111 end, coil core piece-   111A end, coil core piece-   111B end, coil core piece-   112 capacitor-   113 switch, transistor-   114 switch, transistor-   115 transistor-   116 bobbin-   118 air gap-   120 circumferential end, wedge plate-   122 circumferential end, wedge plate-   124 gap-   126 circumferential end, wedge plate-   128 circumferential end, wedge plate-   130 gap, wedge plate-   132 bolt-   134 ramp, wedge plate-   136 ramp, wedge plate-   138 ramp, inner race-   140 inner race-   142 bolt-   144 circumferential end, wedge plate-   146 circumferential end, wedge plate-   148 gap, wedge plate-   150 circumferential end, wedge plate-   152 circumferential end, wedge plate-   154 gap, wedge plate-   156 ramp, wedge plate-   158 ramp, wedge plate-   160 ramp, inner race-   162 chamfer-   164 chamfer-   166 groove-   168 chamfer-   170 chamfer-   172 groove-   174 slot-   176 slot-   178 slip ring retainer-   180 slip ring-   220 wedge clutch-   222 outer race-   224 inner race-   226 circumferential end, wedge plate-   228 circumferential end, wedge plate-   230 gap, wedge plate-   232 circumferential end, wedge plate-   234 circumferential end, wedge plate-   236 gap, wedge plate-   237 bolt-   238 ramp, wedge plate-   239 ramp, wedge plate-   240 ramp, wedge plate-   241 ramp, wedge plate-   242 ramp, inner race-   243 ramp, inner race-   244 chamfer-   246 chamfer-   248 groove-   250 slot-   252 slip ring retainer-   254 slip ring-   300 electromagnetic actuator-   302 outer race-   304 inner race-   306 wedge plate-   308 electromagnetic actuator-   310 coil-   312 coil core piece-   314 end, coil core piece-   316 end, coil core piece-   318 finger, wedge plate

The invention claimed is:
 1. A wedge clutch, comprising: an axis ofrotation; an inner race; an outer race located radially outward of theinner race; a wedge plate radially disposed between the inner race andthe outer race; an electromagnetic actuator including: a coil arrangedto be energized by an electrical power source to displace the wedgeplate, with respect to the inner race or the outer race, to switch thewedge clutch between: a first locked mode of the wedge clutch, in whichthe inner race, the wedge plate, and the outer race are non-rotatablyconnected for rotation of the inner race in a first circumferentialdirection; and, a first free-wheel mode of the wedge clutch, in whichthe inner race is rotatable, with respect to the outer race, in thefirst circumferential direction; and, an attenuating circuit including:a capacitor wired in parallel with the coil; and, a first switch wiredto the capacitor, wherein: during the first free-wheel mode: the firstswitch is arranged to connect the capacitor to an electrical ground;and, the electrical power source is arranged to: energize the coil; and,charge the capacitor with a voltage; and, following an initiation of thefirst locked mode: the first switch is arranged to electrically isolatethe capacitor from the electrical ground; and, the capacitor is arrangedto discharge the voltage through the coil.
 2. The wedge clutch of claim1, wherein following the initiation of the first locked mode, the coiland the capacitor are arranged to alternately drive: first electricalcurrent through the coil in a first direction; and, second electricalcurrent through the coil in a second direction, opposite the firstdirection.
 3. The wedge clutch of claim 2, wherein following theinitiation of the first locked mode, the coil and the capacitor arearranged to alternately drive the first electrical current and thesecond electrical current to randomize residual magnetic fields in theelectromagnetic actuator and attenuate residual magnetic saturation inthe electromagnetic actuator.
 4. The wedge clutch of claim 1, wherein:the attenuating circuit includes a second switch, the second switch:electrically connected to the capacitor; and, arranged to electricallyconnect to the electrical power source; and, following the initiation ofthe first locked mode, the second switch is arranged to electricallyisolate the capacitor from the electrical power source.
 5. The wedgeclutch of claim 1, wherein: the wedge plate includes: a firstcircumferential end; a second circumferential end; and, a gap betweenthe first circumferential end and the second circumferential end; totransition from the first locked mode to the first free-wheel mode, thecoil is arranged to be energized by the electrical power source to: drawthe first circumferential end and the second circumferential end closertogether; and, displace the wedge plate radially inwardly; and, totransition from the first free-wheel mode to the first locked mode: theelectromagnetic actuator is arranged to be de-energized; and, the wedgeplate is arranged to displace radially outwardly.
 6. The wedge clutch ofclaim 5, wherein: the electromagnetic actuator includes only one singlecoil core piece with an end enclosed by the coil; the only one singlecoil core piece is fixedly connected to the first circumferential end;and, the coil is arranged to be energized by the electrical power sourceto displace the only one single coil core piece toward the secondcircumferential end to switch the wedge clutch from the first lockedmode to the first free-wheel mode.
 7. The wedge clutch of claim 6,wherein: the wedge plate includes: a plurality of first ramps slopingradially inwardly in the first circumferential direction; and, aplurality of second ramps sloping radially inwardly in a secondcircumferential direction opposite the first circumferential direction;the inner race includes: a plurality of first ramps sloping radiallyinwardly in the first circumferential direction; and, a plurality ofsecond ramps sloping radially inwardly in the second circumferentialdirection; each first ramp of the wedge plate is in contact with arespective first ramp of the inner race; and, each second ramp of thewedge plate is in contact with a respect second ramp of the inner race.8. The wedge clutch of claim 7, wherein: in the first locked mode of thewedge clutch, the inner race, the wedge plate, and the outer race arenon-rotatably connected for rotation of the inner race in the secondcircumferential direction; and, in the first free-wheel mode of thewedge clutch, the inner race is rotatable, with respect to the outerrace, in the second circumferential direction.
 9. The wedge clutch ofclaim 5, wherein: the electromagnetic actuator includes: a first coilcore piece: fixedly connected to the first circumferential end; and,with an end enclosed by the coil; a second coil core piece: fixedlyconnected to the second circumferential end; and, with an end enclosedby the coil; and, a gap, enclosed by the coil, between the first coilcore piece and the second coil core piece; and, the coil is arranged tobe energized by the electrical power source to displace the first coilcore piece and the second coil core piece toward each other to switchthe wedge clutch from the first locked mode to the first free-wheelmode.
 10. The wedge clutch of claim 9, wherein: the inner race includesa plurality of first ramps sloping radially inwardly in the firstcircumferential direction; the wedge plate includes a plurality of firstramps sloping radially inwardly in the first circumferential direction;each first ramp of the wedge plate is in contact with a respective firstramp of the inner race; and, to transition from the first locked mode tothe first free-wheel mode, the electromagnetic actuator is arranged toslide, in the first circumferential direction, at least first ramp ofthe wedge plate radially inwardly along at least one first ramp of theinner race.
 11. The wedge clutch of claim 10, wherein: in a secondlocked mode of the wedge clutch, the inner race, the wedge plate, andthe outer race are non-rotatably connected for rotation of the innerrace in a second circumferential direction, opposite the firstcircumferential direction; in a second free-wheel mode of the wedgeclutch, the inner race is rotatable, with respect to the outer race, inthe second circumferential direction; the inner race includes aplurality of second ramps sloping radially inwardly in the secondcircumferential direction; the wedge plate includes a plurality ofsecond ramps sloping radially inwardly in the second circumferentialdirection; each second ramp of the inner race is in contact with arespective second ramp of the wedge plate; and, to transition from thesecond locked mode to the second free-wheel mode, the electromagneticactuator is arranged to slide at least second ramp of the wedge plateradially inwardly along at least one second ramp of the inner race. 12.A wedge clutch, comprising: an axis of rotation; an inner race; an outerrace located radially outward of the inner race; a wedge plate radiallydisposed between the inner race and the outer race and including: afirst circumferential end; and, a second circumferential end; anelectromagnetic actuator including: a coil: including a first coil corepiece: fixedly connected to the first circumferential end; and, with anend enclosed by the coil; and, arranged to be energized by an electricalpower source to draw the first circumferential end and the secondcircumferential end toward each other to switch the wedge clutchbetween: a locked mode in which the inner race, the wedge plate, and theouter race are non-rotatably engaged for rotation of the inner race in acircumferential direction; and, a free-wheel mode in which the innerrace is rotatable with respect to the outer race in the circumferentialdirection; and, an attenuating circuit including: a capacitorelectrically wired in parallel with the coil; and, a first switchelectrically connected to the capacitor, wherein: during the free-wheelmode: the first switch is arranged to connect the capacitor to anelectrical ground; and, the electrical power source is arranged to:charge the capacitor with a voltage; and, energize the coil; and,following an initiation of the locked mode: the first switch is arrangedto electrically isolate the capacitor from the electrical ground; and,the capacitor is arranged to discharge the voltage through the coil. 13.The wedge clutch of claim 12, wherein following the initiation of thelocked mode, the coil and the capacitor are arranged to alternatelydrive: first electrical current through the coil in a first direction;and, second electrical current through the coil in a second direction,opposite the first direction.
 14. The wedge clutch of claim 13, whereinfollowing the initiation of the locked mode, the coil and the capacitorare arranged to alternately drive the first electrical current and thesecond electrical current to randomize residual magnetic fields in theelectromagnetic actuator and attenuate residual magnetic saturation inthe electromagnetic actuator.
 15. The wedge clutch of claim 12, wherein:the inner race includes a plurality of ramps sloping radially inwardlyin the circumferential direction; the wedge plate includes a pluralityof ramps sloping radially inwardly in the circumferential direction;each ramp of the wedge plate is in contact with a respective ramp of theinner race; and, to transition from the locked mode to the free-wheelmode: the electromagnetic actuator is arranged to slide at least oneramp of the wedge plate radially inwardly along at least one ramp of theinner race; and, the wedge plate is arranged to displace radiallyinwardly.
 16. The wedge clutch of claim 12, wherein to transition to thefree-wheel mode to the locked mode: the electromagnetic actuator isarranged to be de-energized; and, the wedge plate is arranged todisplace radially outwardly to initiate or increase frictional contactbetween the wedge plate and the outer race.
 17. The wedge clutch ofclaim 12, wherein the electromagnetic actuator includes: a second coilcore piece: fixedly connected to the second circumferential end; and,with an end enclosed by the coil; and, a gap, enclosed by the coil,between the first coil core piece and the second coil core piece; and,the coil is arranged to be energized by the electrical power source todisplace the first coil core piece and the second coil core piece towardeach other to switch the wedge clutch from the locked mode to thefree-wheel mode.